1. Technical Field
The invention relates to a technique for processing an image and a technique for printing the image.
2. Related Art
In recent years, a so-called halftone technique in which an image with the larger number of gradations is displayed or printed using a recording method with the number of gradations smaller than that of the image has significantly advanced in the image processing field. In such a halftone technique, speeding up of processing and improvement in an image quality is required, and how to balance both the speeding up of the processing and the improvement in the image quality has always been an issue in hardware resources having limited capability.
Such balancing is required at various levels. For example, when a dither method and an error diffusion method are cited as a representative example of a halftone method, the former is capable of performing processing at high speed but requires various contrivances for improving the image quality, and the latter is capable of making image quality higher, but it takes a time for the processing and also requires a buffer which temporarily stores an error.
In the meantime, when paying attention to unit for the image processing, a method of processing pixels in a pixel-by-pixel manner and a method of processing a plurality of pixels collectively are considered. In the former, the higher image quality may be easily achieved, but as the resolution becomes higher, the number of pixels to be processed becomes huge. In the latter, the number of pixels to be processed can be suppressed, but the image quality is degraded by the same extent of the suppression. Assuming that a computer that prepares an image and a printer that prints the image are connected to each other, when the computer having a high processing capability performs half toning, there is a case in which the processing can be sped up but an amount of data to be transferred to the printer becomes increased to the point that the data transfer becomes bottlenecked.
The inventors have developed various methods to balance such problems among given hardware resources, and have developed and suggested a method for balancing a dither method and an error diffusion method (see JP-A-2013-115748), a method for processing a plurality of pixels collectively at high speed and with high image quality (see Japanese Patent No. 4225319), or the like.
These methods are excellent methods that optimize high-speed processing and achievement of high image quality under a predetermined condition, but there is room for improvement in the optimization for a case where various types of inks (color ink or monochromatic multi-gradation ink) and the like are used.